Method of producing cutting teeth on cutting tools

ABSTRACT

The disclosure herein describes a method of producing cutting teeth on the blade of a cutting tool; the method consists first in folding longitudinally, by stamping, one part of the blade to an angle of less than about 15*; secondly, in producing, by stamping a portion of the folded part, a series of substantially identical indentations side by side along the edge of the blade, the line separating the stamped and unstamped zones having the appearance of a plurality of juxtaposed arcs subtended by the edge of the blade, the concavity of the indentations extending towards the salient angle side of the fold line; and, thirdly, in carrying out a planing operation on the face of the folded part of the blade located on the reentering angle side of the fold line. The planing operation provides a chamfer in the edge of the blade and, by the removal of the projections formed by the convex part of the indentations, the planing step produces sharp-edged scallops which form the teeth of the cutting tool.

[ June 26, 1973 METHOD OF PRODUCING CUTTING TEETH ON CUTTING TOOLS Rene Chambon, Tarbes-Hautes-Pyrenees, France [75] Inventor:

[73] Assignee: Societe Francaise dEquipment Menager, Lourdes, Pyrenees, France 22 Filed: Nov.4, l97l 21 Appl. No.: 195,679

Primary Examiner Leonidas Vlachos Attorney-Roger Goudreau [57] ABSTRACT The disclosure herein describes a method of producing cutting teeth on the blade of a cutting tool; the method consists first in folding longitudinally, by stamping, one part of the blade to an angle of less than about 15; se-

condly, in producing, by stamping a portion of the folded part, a series of substantially identical indentations side by side along the edge of the blade, the line separating the stamped and unstamped zones having the appearance of a plurality of juxtaposed arcs subtended by the edge of the blade, the concavity of the indentations extending towards the salient angle side of the fold line; and, thirdly, in carrying out a planing operation on the face of the folded part of the blade located on the reentering angle side of the fold line. The planing operation provides a chamfer in the edge of the blade and, by the removal of the projections formed by the convex part of the indentations, the planing step produces sharp-edged scallops which form the teeth of the cutting tool.

3 Claims, 16 Drawing Figures Patented June 26, 1973 3,741,046

3 Sheets-Sheet 1 r vllllflllll r I; I

Inventor RilNl; CHAMBUN BALW Patented June 26, 1973 3,741,046

3 Sheets-Sheet 3 I noenlor R CHAMBUN A Ilorney Patented June 26, 1973 3,741,046

3 Sheets-Sheet 3 FIG. 9c FIG. 9d

I nvenlor RENQMBON A Home y This invention relates to a new method for producing cutting teeth on the blade of a cutting tool such as a knife, clippers or like articles. The invention further relates to the serrated blades obtained by such a method and extends to a particular application of these blades for the production of automatically operating knives.

The conventional method of producing teeth on a blade is to machine each tooth to the desired profile along the edge of the blade by means of grinding machines. These grinding operations have a considerable effect on the cost of the blade: the initial setting of the grinding machines is a delicate and lengthy operation and the grinding operation itself takes some time and involves considerable wear of the grindstones.

It is an object of this invention to provide a toothed blade for a cutting tool, the cost price of which being very much less than that of a conventional blade; this is due to a considerable reduction in the cost of the operations by means of which the teeth are produced.

In a first form of the invention, the rough blade is in the form of a metal strip of less than twenty tenths of a millimeter in thickness. The method according to the invention consists in:

folding longitudinally, by stamping, one part of the strip to an angle of less than about the fold line being straight and parallel with the longitudinal edge of the strip;

producing, by stamping a portion of the folded part, a series of substantially identical indentations arranged side by side along the edgeof the folded part, the line separating the stamped and unstamped zones having the appearance of a plurality of juxtaposed arcs subtended by the edge of the strip, the concavity of the said indentations extending towards the salient angle side of the fold line formed by the first folding step;

carrying out a planing operation on the face of the folded part of the blade located on the reentering angle side of the fold line formed by the first folding step, the said planing operation being intended to provide a chamfer in the edge of the said strip and, by the removal of the projections formed by the convex parts of the indentations, to produce sharp-edged scallops which form the teeth.

Teeth are thus produced along the entire length of the blade by simple stamping operations, which are extremely fast; a single finishing operation consists in producing, with a grindstone, a plane surface of one face of the blade. This planing operation, which is carried out simultaneously on all of the teeth in the blade, causes no setting difficulties and may be carried out in a very short time. It may be gathered from the foregoing that the cost of the method described is very low, an important factor in the cost price of the finished blade.

It should also be noted that the linear folding step and the indentation producing step may be carried out simultaneously in a single stamping operation, which make it possible to reduce handling time and the time taken to produce the teeth.

According to another form of the present invention, the rough blade is in the form of a metal strip, less than twenty tenths of a millimeter in thickness, and comprising a chamfered zone located along one longitudinal edge; in this case, the initial folding operation becomes superfluous, and the method is reduced to the production, by stamping one part of the chamfered zone, of a series of indentations similar tothose described above and a planing operation on the stamped portion on the face opposite the chamfer where the indentations proj- CCL.

The planing operation provided for by this method consists, preferably, in machining the face located on the side on which the indentations project, in such a manner that all its points are brought to the side of the flat unstamped part of the face.

According to another form of the invention, the rough blade may be in the form of a metal strip, less than about ten tenths of a millimeter in thickness, having an inwardly curved profile provided with a flat edge at an angle to the mean transverse direction of the blade. In this case, the initial folding operation again becomes superfluous, and the method is reduced to the production, by stamping a portion of this flat edge, of

a series of indentations similar to those described above, followed by a planing operation of the stamped portion of the blade on its concave face, where the indentations project. The inwardly curved profile imparts to the blade adequate rigidity, while the reduction in the thickness thereof results in substantial savings in material.

The invention also relates to any blade in which the teeth are produced by the process described above or alternatives thereof; it will be noted, in particular, that the scalloped portions, located between the teeth of the blade, have a shape which is rounded, continuous, and lacks any sharp edges where it joins the said blade.

Finally, the invention covers numerous applications of .the present blade. Two such blades, for example may be joined together by one face to produce an automatically operating knife, in which case the blades are provided with a drive especially an electrical drive causing them to vibrate in the longitudinal direction.

The invention will be better understood if the following description is read and the attached drawings are examined, the said drawings illustrating, in the form of nonrestrictive examples, certain forms of execution of the invention. In these drawings:

FIGS. 1, 2, 3, 4 illustrate schematically a knife blade with the teeth at various stages of production;

FIGS. 30 and 4b are sections taken through planes aa and b-b of FIGS. 3 and 4, respectively;

FIGS. 5, 6, 7 illustrate, in a variant, a similar method of producing the teeth;

FIGS. 6c and 7d are sections taken through planes c-c and d-d in FIGS. 6 and 7, respectively;

FIG. 8 shows an application of the toothed blades according to the invention;

FIGS. 9a, 9b, 9c, 9d show various ways of producing teeth on a blade having an inwardly curved profile.

According to a first form of the invention, the method consists in folding a strip 1 along a fold line 2 which is straight and parallel with the longitudinal edges of the strip. The strip 1 is about twelve tenths of a millimeter in thickness; it is about half a centimeter in width, and about twenty centimeters in length. The width of the folded portion 3 is between 7 and 8 millimeters, and the angle of the fold is about 10. This fold is produced by applying to the portion 3 appropriate pressure by means of a press, as indicated by the arrows in FIG. 2. 7 A

The following operation is shown separately, in FIG. 3, for the sake of clarity, from the folding operation although it can be carried out simultaneously therewith; it consists in producing a series of indentations such as those indicated at 4 on a portion of the folded part 3. A line of demarcation 5, which defines the stamped zones, has the appearance of a series of arcs subtended by the edge of the blade. These indentations are obtained by applying, with a press, suitable pressure on the zones to be indented. The maximal amount of deformation in the central area of each indentation 4, at the level of the edge of the blade, may be set to a value of between about five and fifteen tenths of a millimeter, depending upon the desired configuration of the tooth to be produced. The width of an indentation, which is the distance between intersection lines 6 and 7 of the arc with the edge of the blade, is equal to the desired width of the tooth to be produced. FIG. 3a shows a section through the blade. It will be seen that the blade has undergone no deformation here while the indentations were being formed.

The final operation consists in planing the blade, through grinding or otherwise, the plane r-r shown in FIG. 3a. The cutting edge of the blade is thus chamfered, while the indentations shaved by this planing produce, on the edge of the blade, a series of sharpedged scallops arranged side by side and forming the teeth of the blade. FIG. 4b is a section through plane b-b at the apex of a tooth.

By means of rapid stamping and planing operations affecting the entire blade at once, it is now possible to obtain cutting teeth without grinding each tooth individually.

FIG. 5 shows a blade 9 having a chamfer 10. The procedure for producing teeth on a blade of this kind is similar to that described above, but there is no longer any folding operation. Instead, a series of indentations is produced on the chamfered portion of the blade, after which planing is carried out along the plane r-r (FIG. 6c) of the unchamfered face. This produces a blade similar to those already described.

Blades of this kind have numerous applications, such as saws, knives, clipper blades, or like articles. FIG. 8 shows two blades 12,13 fastened together on their flat faces and provided with teeth 14 and 15, respectively, as produced by the method according to the invention. These blades may vibrate longitudinally in relation to each other, in order to produce an automatic cutting tool, for example an electric knife.

FIGS. 9a, 9b, 9c, 9d show the method of the present invention applied to special blades which are fastened together in pairs to form automatically operating knives. These blades are between about six tenths and ten tenths of a millimeter in thickness and have a curved profile, as shown in FIG. 9a. This profileprovides adequate rigidity in the blades while making it possible to obtain considerable savings in material, since such blades may be substantially thinner than flat blades. I

As applied to this type of blade, the present method consists in producing a series of indentations similar to those illustrated in FIG. 3 on a flat portion 17 (with which this type of blade is provided), the flat portion being at a slight angle to the mean direction of the profile.

FIG. 9b is a section, after the indentations have been formed, through a blade at a point of maximal indentation. The subsequent operation consists in planing the blade along the plane r-r containing a flat portion 18 thereon, which will allow it to be fastened to another identical blade. FIG. 9c is a section through the planed blade.

Finally, FIG. 9d illustrates schematically how two toothed blades, produced as indicated above, are fastened together to form an automatic cutting tool.

Three specific forms of the method according to the invention have been described above: it is wished to have it understood that the method is not limited in interpretation except by the terms of the following claims.

What is claimed is:

1. A method of producing cutting teeth on the blade of a cutting tool, said blade being in the form of a metal strip, comprising the steps of:

folding longitudinally, by stamping, a part of the strip to an angle of less than about 15, the fold line being straight and parallel with a longitudinal edge of said strip; said fold line having a. salient angle side and a reentering angle side;

producing, by stamping a portion of the folded part,

a series of substantially identical indentations arranged side by side along the edge of the folded part, the line separating the stamped and unstamped zones having the appearance of juxtaposed arcs subtended by the edge of the strip, the concavity of the said indentations extending towards the salient angle side of the fold line formed by said folding step; and

carrying out a planing operation on the face of the folded part of the strip located on the reentering angle side of the fold line, said planing step being intended to provide a chamfer in the edge of the said strip and to produce sharp-edged scallops by removing projections formed by the convex parts of the indentations.

2. A method as defined in claim 1, characterized in that the planing consists in machining the face located on the side on which the indentations project, so that all its points are brought to the side of the flat unstamped part of the said face.

3. A method as defined in claim 1, characterized in that the folding step and the indentations producing step are carried out simultaneously in a single stamping operation.

I I t t i 

1. A method of producing cutting teeth on the blade of a cutting tool, said blade being in the form of a metal strip, comprising the steps of: folding longitudinally, by stamping, a part of the strip to an angle of less than about 15*, the fold line being straight and parallel with a longitudinal edge of said strip; said fold line having a salient angle side and a reentering angle side; producing, by stamping a portion of the folded part, a series of substantially identical indentations arranged side by side along the edge of the folded part, the line separating the stamped and unstamped zones having the appearance of juxtaposed arcs subtended by the edge of the strip, the concavity of the said indentations extending towards the salient angle side of the fold line formed by said folding step; and carrying out a planing operation on the face of the folded part of the strip located on the reentering angle side of the fold line, said planing step being intended to provide a chamfer in the edge of the said strip and to produce sharp-edged scallops by removing projections formed by the convex parts of the indentations.
 2. A method as defined in claim 1, characterized in that the planing consists in machining the face located on the side on which the indentations project, so that all its points are brought to the side of the flat unstamped part of the said face.
 3. A method as defined in claim 1, characterized in that the folding step and the indentations producing step are carried out simultaneously in a single stamping operation. 